The engine is a 350 LZ9 from a 1984 C-30 Chevy van. The carb will be a Holley 750 cfm with vacuum secondaries, the heads will be Edelbrock Performers with 64cc chambers, and it also has a 7-quart Moroso oil pan. I want to bore the block to .030 over and use one of your rebuild kits.

What compression is more acceptable for street use with pump gas—9.73:1 or 10.9:1?